Congestive heart failure is a debilitating and progressive disease that causes a heart to pump less efficiently over time. Typically, the heart has been weakened by an underlying problem, such as clogged arteries, high blood pressure, a defect in heart muscles or heart valves, or some other medical condition. The progression of congestive heart failure is often caused by the heart's own efforts to compensate for weakening of the heart. In particular, portions of the heart, particularly the ventricles, can become increasingly enlarged as the heart tries to compensate for weakening of the heart muscles. As the heart enlarges, the heart performs an increasing amount of work to supply blood through the vasculature of a body. Over time, the heart can become so enlarged that the heart can no longer provide an adequate supply of blood to the body. As a result, individuals afflicted with congestive heart failure often experience shortness of breath and fatigue even when performing simple daily activities. Moreover, as the heart enlarges, the heart valves may not adequately close, thus further reducing the heart's ability to supply blood to the body.
Drug therapies have been developed to treat individuals afflicted with congestive heart failure. Existing drug therapies can alleviate the symptoms of congestive heart failure and can sometimes slow the progression of congestive heart failure. However, existing drug therapies typically are unable to halt or reverse the progression of congestive heart failure. Moreover, existing drug therapies can sometimes produce adverse side effects. Surgical procedures have also been developed to treat congestive heart failure. Examples of existing surgical procedures include the Batista procedure and cardiomyoplasty. However, such existing surgical procedures can be invasive, risky, and expensive while providing limited improvements in cardiac performance.
In light of the shortcomings of existing drug therapies and existing surgical procedures, attempts have been made to treat congestive heart failure with cardiac jackets. An existing cardiac jacket can be fitted to an enlarged heart to limit expansion of the heart during diastole. While an existing cardiac jacket can impede further enlargement of the heart, such cardiac jacket is typically a passive device that does not provide active assistance to the heart during systole. Moreover, the size of an existing cardiac jacket typically cannot be readily adjusted over time to reverse the enlargement of the heart. In particular, once an existing cardiac jacket is implanted within a body, adjusting the size of such cardiac jacket typically requires further surgical procedures, which can be invasive, risky, and expensive.
It is against this background that a need arose to develop the cardiac apparatus and methods described herein.